[Distribution Characteristics and Health Effects of Bioaerosols in Spring over Xi'an City].

A large amount of fluffy caktins appears in spring in Xi'an that may cause air pollution and lead to health risks such as asthma. In this study, bioaerosol, PM2.5, and fluffy catkins were collected from different sample points (traffic site and campus site) in Xi'an in spring. The variations in bioaerosol, fluffy catkins, and the bacterial community structure were investigated using culture-dependent and high-throughput sequencing methods. The results showed that the concentration of culturable bacteria was significantly higher (P=0.027) at the traffic site. The concentration of culturable bacteria at the traffic site was 2.7 times that of fungi, whereas the concentration of culturable fungi at the campus site was 1.4 times higher than that of bacteria. The peak concentrations of culturable bacteria and fungi appeared at 08:00 a.m. The size distribution of culturable bacteria showed a bimodal pattern, whereas that of culturable fungi showed a unimodal distribution. Soil and vegetation were the main sources of atmospheric microorganisms (85.9%), and Proteobacteria was the most abundant phylum in both fluffy catkins and PM2.5, accounting for 91.3% (traffic site) and 99.1% (campus site) of the fluffy catkins. Actinobacteria, Firmicutes, Bacteroidetes, Cyanobacteria, and Deinococcus-Thermus were the dominant phyla in PM2.5. Some genera were opportunistic pathogen bacteria in the fluffy catkins, such as Enterobacter and Pseudomonas, which can lead to infection and diarrhea risks. These results could provide fundamental data on potential health risks of spring-borne bioaerosols.

Convenient One-Step Synthesis of Benzo[c]phenanthridines by Three-Component Reactions of Isochromenylium Tetrafluoroborates and Stilbenes in Acetonitrile.

A new type of three-component reaction of air-stable isochromenylium tetrafluoroborates with electron-rich stilbenes in acetonitrile has been developed under catalyst-free conditions in this work. This cascade multibond-formation reaction is initiated by an intermolecular oxa [4 + 2]-cycloaddition, relayed with a nucleophilic addition of acetonitrile, and terminated by an intramolecular Friedel-Crafts reaction, affording the corresponding benzo[c]phenanthridine analogues in one step.

[Hsa-miR-654-5p regulates osteogenic differentiation of human bone marrow mesenchymal stem cells by repressing bone morphogenetic protein 2].

OBJECTIVE: To study the effect of hsa-miR-654-5p in repressing bone morphogenetic protein 2 (BMP2) mRNA and protein in human bone marrow mesenchymal stem cells (hBMSCs), and explore its regulatory role in osteogenic differentiation of hBMSCs. METHODS: hBMSCs in the 4th passage were cultured for 16 h and transfected with hsa-miR-654-5p followed by further culture for 48 h. qRT-PCR and Western blotting were performed to detect the expressions of BMP2 mRNA and protein. Dual-luciferase?reporter gene assay was employed to examine the repression of the BMP2 gene. RESULTS: BMP2 mRNA and protein expressions were significantly down-regulated in hBMSCs with hsa-miR-654-5p overexpression. Dualluci-ferase reporter gene assay indicated that the predicted target site of BMP2 was repressed directly by hsa-miR-654-5p, but this repression did not occur at the mutant predicted target site of BMP2. CONCLUSION: hsa-miR-654-5p can directly repress the mRNA and protein expressions of BMP2 by binding to a specific target site. The changes in hsa-miR-654-5p can play an important role in osteogenic differentiation regulation of hBMSCs.

[New research progress on atrophic nonunion].

Occurance of atrophic nonunion is a complex process. Previous studies suggested that atrophic nonunion was mainly due to lack of blood supply of fracture fragments, but recent studies found that blood supply was not deficiency in middle and late stages, indicating that decreased osteogenic factors and blood supply in early stages might play an important role in morbidity. Current effective treatment measures for atrophic nonunion mainly include bone graft and fixation,physical therapy, local injection therapy. All-round preventive could reduce incidence of atrophic nonunion. Atrophic nonunion is still a troublesome complication of fractures in orthopaedics, and more attention should be paid for its effective prevention and treatment. The paper summarized recent original articles about atrophic nonunion and reviewed the occurrence mechanisms, diagnosis, prevention and treatment measures of this disease.